This invention relates generally to miter gauge devices for use with cutting tools and the like, and more particularly to an improved miter gauge and method for setting the miter angle with high precision.
Various cutting tools for use with either metal or wood cutting devices such as table saws, jigsaws, band saws and the like, use a miter gauge to establish the miter angle between a workpiece and the cutting blade of the device and guide the workpiece into the cutting blade at the selected miter angle. Typically, these guides consist of an elongated rectangular slide bar which slides in a similar sized groove in a flat surface of the cutting device over which the workpiece slides as it engages the cutting blade. The groove extends parallel to the cutting line of the device such that the guide line of the miter guide is parallel thereto. A slotted semi-circular frame is pivotally mounted on the slide bar and is provided with a protractor type angular indicia typically between 0.degree. and 60.degree. on each side of the guide line to set the desired miter angle. A combination handle and screw extends through a slot in the frame to clamp the frame at the selected angle with the slide bar. The frame includes a planar guide surface or fence which is disposed at right angles to the flat surface of the cutting device against which the workpiece is held as it is moved into the cutting blade.
These typical miter gauges are limited in accuracy due to the introduction of human error in reading the angular indicia, particularly for non standard angles in which the operator must guess the location of fractions of angles between the graduation of the angular indicia on the gauge.
Various means have been proposed in the art to increase the resolution at which the miter angle can be set including enlarging the size of the semicircular frame in order to increase the gauge indicia resolution by increasing the radius of the location of the indicia from the pivot point. Another means is disclosed in U.S. Pat. No. 4,514,909, issued May 7, 1985, for "Miter Gauge," by Curtis R. Gilbert. In this device, the pivotally mounted frame includes a ring gear mounted atop a post at the pivot point which turns with the pivotal frame and engages a pinion gear attached to a rotatably mounted angle index dial mounted on the guide bar. The index dial is graduated to show the miter angle at which the gauge is set. The gears are operative to rotate the angle index dial through a greater angle than the miter angle by a ratio of six-to-one to increase the resolution with which the miter angle is set.
Although the rotatably mounted angle index dial may improve the accuracy in which miter angles may be set and fractions more correctly interpolated over typical gauges, the mechanism adds complication to the miter gauge and makes the gauge hard to handle due to the added gears and large angle index dial necessary to increase accuracy. Thus, it will be seen that there is a need for an improved miter gauge which is simple to operate and does not add increased size and complication to the gauge mechanism.
In view of the above need it is an object of the present invention to provide a miter gauge and method which substantially improves the resolution with which a miter angle may be set on a miter gauge without complicated additional hardware and mechanical parts.
Another object of this invention is to provide a miter gauge and method in which the resolution is increased without increasing the size of the pivotally mounted frame of the gauge on which the angular indicia is provided.
Other objects and many of the attendant advantages of the present invention will become obvious to those skilled in the art from the following detailed description taken in conjunction with the drawings.